In the design, engineering, and construction of gas turbines, such as jet engines, turbo-prop engines, and other devices, vanes are used for a variety of purposes. For example, in the compressor section of such gas turbines, a multiplicity of blades are affixed to a rotor, usually in circumferential rows, for the purpose of increasing the volume and pressure of the air being introduced into the combustion section of the engine. Vanes add fixed to the fixed portion of the engine surrounding the rotor are positioned at the entrance of the compressor section and immediately behind the rows of rotor blades. These blades serve as guides to ensure that the flow of air comes at each of the rotor blades substantially along a fixed, pre-determined path of travel, so that the blades will function properly. By this means, phenomena such as angular set induced by rotation of the rotor are effectively nullified. The vane structures typically are very complex geometrically. Usually, they are in the general shape of a regular air-foil, having a flat or slightly concave base and an opposing surface in the shape of a section of a parabola. They may be of substantially uniform cross-section geometrically and dimensionally throughout their length, or may be of a varying dimensions and/or cross-sectional shapes along their length, and may taper down in the direction of their tips. Further, typically they twist slightly along their length, and such twisting may or may not be in a uniform amount per unit of distance along the blade. Difficulties encountered in the manufacture of the vast variety and complexity of such devices have been accommodated by forming such vanes according to the teachings of my U.S. Pat. No. 4,483,168, to which reference is made.
As the technology of building such engines has advanced, the performance requirements of the vane structures have also changed. More particularly, the vanes in the compressor section experience the passage of air at up to supersonic speeds, and therefore are subjected to severe resonances, vibration, and pressures. In addition, they tend to become iced-up, particularly in the region of their leading edges. The icing phenomenon, which is a common occurrence under certain atmospheric conditions with an airfoil past which air is moving, and the causes and physical bases for which are now well known, is a phenomenon of particular concern in this context. It often effectively changes the shape of a vane so radically as to disrupt its ability to perform its intended functions efficiently and/or in accordance with its design parameters. Therefore, to preclude this from happening, there is an emerging interest in vanes which are adapted to have temperature-altering fluids, such as heated air, pass through them. Such fluids, after having passed through the vane, may be discharged through the outer surfaces of the vane into the air stream passing through the engine, or they may pass in one end of the vane and out the other for subsequent discharge at a different location.
There are several problems involved in making such vanes. First, as a practical matter, it is virtually impossible to form such devices totally from solid pieces of material, or to cast or forge them, with the internal channels and cavities that are necessary to distribute the fluid through the vane as desired. The environment in which the vanes are used is such as to require the use of metals, such as Inconel or stainless steel, which are very hard and difficult to machine, cast, forge, bore or otherwise alter appropriately. Further, the exterior geometry of such vanes is governed by design parameters which are germane primarily to what is desired to occur with respect to air-flow, and to which, therefore, other design considerations must yield. Those air flow design considerations typically at least complicate and sometimes even render impossible facilitating the kind and extent of interior cavitation and channeling that is required. On the other hand, simply to form a hollow vane from sheet metal with a desired outer surface configuration, for example, has proved not to be satisfactory. Such a construction lacks the strength and durability necessary to withstand the rigors of the severe environment in which such vanes typically are used
Accordingly, it is within the contemplation of this invention to overcome these difficulties by producing vanes having fluid passage capability, comprising an interior support structure upon which is retentively positioned an exterior cover member of desired outer configuration for a vane, wherein the exterior surface of the support member is so configured and dimensioned as to form, together with the interior surfaces of the cover, passageways and cavities of desired dimensions, configurations, and locations to effect distribution of the fluids as desired for their intended purposes.
However, such internal support structures typically must be very complex in shape and configuration in order to create, in combination with the cover member, the desired configuration of conduits and chambers for fluids. Particularly with respect to the materials from which they must be made, such as Inconel or stainless steel, they are difficult or not feasible to produce in final form by casting, forging, machining, boring, or other traditional means. Therefore, it is also within the contemplation of this invention that such support members may be the product of having been made in accordance with the teachings of my U.S. Pat. No. 4,483,168.
Accordingly, an object of this invention is to produce gas turbine vane adapted for the passage of fluids therethrough.
Another object of this invention is to provide vanes which achieve the foregoing objective, in a wide variety of complex external shapes and dimensions.
Still another object of this invention is to produce vanes which achieve one or more of the foregoing objectives wherein each vane comprises a support structure upon which is retentively positioned an outer cover having an outer surface of desired shape and configuration .
Yet another object of this invention is to produce vanes which achieve one or more of the foregoing objectives, having a support member which is so dimensioned and shaped that its outer surface, in combination with the inner surface of an outer cover retentatively position thereon, forms internal fluid passageways and cavities of desired shapes locations, and configurations.
Another object of this invention is to produce vanes which achieve one or more of the foregoing objectives, each of which has an internal support structure that is the product of having been formed in accordance with the teachings of U.S. Pat. No. 4,483,168.